The invention relates to a combined night/day viewing apparatus for an armoured venicle. A single housing includes a night path and a day path as well as a first movable input reflector for causing the input light beams originating from the field of view to deviate at least in the direction of the optical axis of the night path. The night path is constituted by an objective, a light intensifier tube and an ocular. The day path is constituted by an optical system having an enlargement 1 magnification comprising at least one second output reflector.
The viewing apparatus according to the invention is such that the enlargement is equal to 1 for the day path and is of the order of 1 for the night path. For both paths attempts are made to obtain the largest possible field of view. Through this kind of apparatus, which is arranged so as to traverse the armouring of a vehicle, the view is periscopic. The invention is used more particularly for an episcope for driving a tank.
The French Utility Models Nos. 2,377,647 and 2,377,648 disclose a night/day viewing apparatus, that is to say an optical periscopic apparatus contained in a single housing that can be used for all the degrees of illumination of the object viewed, both with a bright sky and in the night with a clouded sky. When such an apparatus is arranged in an armoured car, it can consist of a hermetic assembly that can be arranged in the standardized opening provided until now for receiving both night viewing apparatus and day viewing apparatus. These technical characteristics and these functions are also examined at the beginning for the viewing apparatus described hereinafter. In fact it is very disadvantageous in both cases to use immovable distinct optical apparatus for the night and the day, especially because of the necessity on the one hand to proceed to switching operations, during which the view through the optical apparatus is no longer possible, and on the other hand to be forced to arrange the apparatus not utilized without the risk of damage of the latter or of congestion of the dwellingplace of the vehicle, which is tiny.
A compact construction comprising a single housing of standardized dimensions can be comparatively readily obtained in a viewing apparatus, for which the fields of view are narrow, i.e. of the order of 5.degree. to 10.degree., and for which the enlargements obtained are substantial, i.e. of the order of 5 to 10, the vehicle provided with the viewing apparatus being normally stationary during viewing. On the contrary, viewing has to take place with a normal view, especially for driving vehicles, i.e. for a small enlargement equal or substantially equal to unity, which takes place with a large field of view. A largest possible field of view is desired and it has to be ensured that the compact construction obtained due to the combination of a day viewing apparatus and a night viewing apparatus in the same housing is not accompanied by a reduction of the field of view.